Unique, common, and interacting cortical correlates of thirst and pain.
This study used positron-emission tomography to establish the patterns of brain activity involved in the isolated and concurrent experiences of thirst and pain. Ten subjects were scanned while experiencing pain evoked with noxious pressure, while experiencing thirst after the infusion of hypertonic saline, and while experiencing pain when thirsty. After the onset of thirst, noxious pressure evoked more intense sensations of pain. Noxious pressure did not change subjective ratings of thirst. Thirst caused activation in the anterior cingulate (Brodmann area 32) and the insula. Enhanced pain responses were associated with increased activity in cortical regions that are known to correlate with pain intensity, and also with unique activity in the pregenual anterior cingulate and ventral orbitofrontal cortex. These findings suggest a role for limbic and prefrontal cortices in the modulation of pain during the experience of thirst.
Proc Natl Acad Sci U S A. 2006 Feb 14;103(7):2416-21. Epub 2006 Feb 3.
Howard Florey Institute, Centre for Neuroscience, and Department of Physiology, University of Melbourne, Parkville, Victoria 3010, Australia. m.farrell@hfi.unimelb.edu.au
